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Though Environment Canada had issued a Special Weather Statement early in the afternoon, the severe thunderstorm warning for Toronto, Vaughan, Richmond Hill, Markham, Brampton and Mississauga wasn’t issued until 5:55 p.m., long after the hardest part of the storm had passed through the area.

Mark Seifert, a meteorologist with Environment Canada said that thunderstorms are “notoriously difficult” to predict. “Until they develop.”

A woman gets gets back in her car in flood water on Lakeshore West during a storm in Toronto on Monday, July 8, 2013. THE CANADIAN PRESS/Frank Gunn

THE CANADIAN PRESS/Frank Gunn

A woman walks back to her flooded car after discovering that the firetruck behind her had suffered the same fate on the Toronto Indy course on Lakeshore Boulevard in Toronto on Monday, July 8 2013. THE CANADIAN PRESS

THE CANADIAN PRESS

Christie Pitts after a heavy rain storm July 8, 2013.

David Skok/Global News

Fire crews trying to get people out of a stuck GO Train in Toronto on July 8, 2013.

“Thunderstorms formed around 3 p.m. this afternoon to the west and north of Toronto and converged on the city around 5 p.m. The combination of tropical air, weak steering winds causing very slow moving storms, and thunderstorms redeveloping over the same area created the perfect ingredients for flooding.”

Once it was apparent that the slow-moving system had dumped more than 40mm of rain in areas, Environment Canada issued a severe thunderstorm warning.

“It was basically, a couple of thunderstorms that passed over an area. What resulted was a high rain,” said Seifert. “And we had two things contribute to it: first, were storms that produced heavy rain; the second that it was a slow-moving system.”

Seifert said that the problem for Toronto is that the rain has nowhere to go. In a concrete city, the sewers can’t handle the intense rain.

Siefert added that the storms resulted in heavily localized flooding: whereas Toronto has seen 90 mm and Pearson has seen 106 mm, Buttonville Airport in Markham received only 17. Hamilton has received negligible rain.

The average rainfall for July is 74 mm. The single day record for rainfall is 121.4 mm set during Hurricane Hazel on October 15, 1954.

Though the rain is continuing, it looks as if most of it will pass west of the city, affecting Brampton and Mississauga.

Seifert added that the forecast is much of the same over the next two days: hot, humid with a chance of thunderstorms.